In recent years, as display panels used in display devices such as digital televisions, display panels have been implemented in which a plurality of pixels made from light-emitting elements such as organic light-emitting elements are arranged in column and row directions on a substrate. A typical, publicly-known configuration of such a display panel is one in which drive circuits each made from a plurality of thin film transistors (TFT) are each disposed in a line-shape, an insulating layer is disposed on the drive circuits, and, for each drive circuit, a plurality of light-emitting elements is connected thereto, disposed on the insulating layer in a line. In such a display panel, typically, source and gate lines extending in the column or row directions from the thin-film transistors disposed on the substrate are connected to output power of drivers via external connection terminals disposed on a periphery of the substrate (for example, see Patent Literature 1).
FIG. 15 shows an example cross-section taken along a direction of a source line of a substrate used in a conventional display device. As shown in FIG. 15, a metal wiring layer pattern 1207 is disposed on an upper surface of a substrate 1100, an insulating layer 1216 is disposed on the metal wiring layer pattern 1207, and a connecting wiring layer pattern 1237 made from, for example, indium tin oxide (ITO) is disposed on an upper surface of the insulating layer 1216. The metal wiring layer pattern 1207 and the connecting wiring layer pattern 1237 are electrically connected to each other via a contact hole 1216a provided in the insulating layer 1216. The metal wiring layer pattern 1207 is connected to a source electrode 117 of a thin-film transistor disposed to the right of the drawing. The source electrode 1107 is electrically connected to an output terminal (not illustrated) of a source driver via a connecting terminal 1237a of the connecting wiring layer pattern 1237 disposed to the left of the drawing.